Upregulation of miR-874-3p and miR-874-5p inhibits epithelial ovarian cancer malignancy via SIK2.

Based on miR-874 expression levels in the GSE47841 microarray, we hypothesized that the mature products of miR-874, miR-874-3p, or miR-874-5p, would inhibit epithelial ovarian cancer (EOC) cell proliferation, metastasis, and chemoresistance. We first examined miR-874-3p and miR-874-5p expression levels in primary EOC tumor tissue samples and found that they were significantly decreased. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) cell proliferation and transwell assays revealed that miR-874-3p and miR-874-5p significantly inhibit EOC cell proliferation, migration, and invasion. Then, using MTT and soft agar assays of paclitaxel-treated Caov3 and SKOV3 cells transfected with miR-874-3p and miR-874-5p, we found that miR-874-3p and miR-874-5p enhance EOC cell chemosensitivity. We then confirmed that serine/threonine-protein kinase 2 (SIK2) was a target gene of miR-874-3p and miR-874-5p. Overall, the results of this study indicate that SIK2 expression can serve as a prognostic biomarker for EOC and that miR-874-3p and miR-874-5p have the potential to enhance clinical treatment of EOC.